waggledanse

hi guys, i'm new to this kind of thing so any help greatly appreciated. I have a 51-plate citroen xsara 2.0 16v sx, and there is a 'rattling' type noise whenever i accelerate. it happens whatever speed i am doing. to best descibe it as; its like a hollow pipe with something rattling inside, coming from the front of the car, maybe towards the rear of the engine. it doesn't rattle when i start the engine up, or when it is stood idle, only when i accelarate. i dont know much about engines and the like, so any help would be great. thanks.